1. Field
The following description relates to an organic light-emitting device.
2. Description of the Related Art
Organic light-emitting divides (OLEDs), which are self-emitting devices, have advantages such as wide viewing angles, excellent contrast, quick response, high brightness, excellent driving voltage, and can provide multicolored images.
A typical device has a structure including a substrate, and an anode, a hole transport layer (HTL), an emission layer (EML), an electron transport layer (ETL) and a cathode which are sequentially stacked on the substrate. The HTL, the EML, and the ETL are organic thin films formed of organic compounds.
An operating principle of an OLED having the above-described structure is as follows.
When a voltage is applied between the anode and the cathode, holes injected from the anode move to the EML via the HTL, and electrons injected from the cathode move to the EML via the ETL. The holes and electrons (carriers) recombine in the EML to generate excitons. When the excitons drop from an excited state to a ground state, light is emitted.
There has been an ongoing demand for a material having improved electrical stability, high charge-transfer or emission capability, a high glass transition temperature that is high enough to prevent crystallization, in regard to existing unimolecular materials.